1. Field of the Invention
The present invention relates to an optical disk device having a motor. More particularly, the present invention relates to an optical disk device having a motor, and of which an optical pickup can be positioned exactly in relation to a spindle associated with the motor.
2. Description Related to the Prior Art
An optical disk such as a CD-R and DVD is an optical information recording medium widely used in a personal computer or other electronic equipment. An optical disk drive or player as optical disk device is incorporated in electronic equipment, for example a portable type referred to as a notebook type of computer, and is used to drive the optical disk. The optical disk drive includes a disk rotating mechanism, and an optical pickup head. The disk rotating mechanism rotates the optical disk at a high speed on a disk tray. The optical pickup head moves in a radial direction of the optical disk, and records information thereto by application of a laser beam. Also, the optical pickup head reads information by receiving laser beam reflected by the optical disk.
A carriage is a pickup moving mechanism, and has the optical pickup head supported thereon. There is a base plate, on which rail shafts are secured to keep the carriage movable in a radial direction of the optical disk. A motor plate is connected with the base plate. On the motor plate, a spindle motor is disposed for rotating the optical disk. A first hole is formed in the motor plate. A screw hole is formed in the base plate. A spacer having a spacer boss is disposed between the motor plate and the base plate. An insertion hole is formed in the spacer boss. The spacer boss is inserted in the first hole of the motor plate, before a screw is helically engaged with the screw hole through the first hole and the insertion hole, to fasten the motor plate and the base plate with the spacer in the squeezed state.
Recently, information recording density of the optical disk has become higher and higher. Thus, high precision is desired in positioning of the optical pickup head and the spindle motor. It is essentially important to keep precision high in assembling the motor plate with the base plate. Precision of the sizes of the base plate, the motor plate and the spacers themselves is also important.
JP-A 2000-331442 discloses a guide shaft securing mechanism for a disk drive, including a support and a guide post portion. The support supports a guide shaft for moving the optical pickup head in the disk radial direction. The guide post portion receives the motor plate for the spindle motor. The support is kept in contact with the guide post portion for positioning the support.
In JP-A 2000-331442, a guide post shaft of the guide post portion is inserted in a first hole of the motor plate. Then screws are fastened to secure the motor plate on the guide post portion. However, sufficient clearance is required between the guide post shaft and the first hole in order to insert the guide post shaft of the guide post portion in the first hole of the motor plate. A problem arises in offsetting of the guide post portion relative to the motor plate, namely offsetting of the spindle motor relative to the optical pickup head, to the degree corresponding to the clearance. Failure in correct playback or recording of information occurs with the optical pickup head when the position of the spindle motor relative to the optical pickup head is incorrect.